1. Field of the Invention
The present invention relates to data transfer switches, specifically to a switch for use in a secondary storage device of a computer system and, more specifically, to a switch for connection between a disk controller and a disk array, and a data transfer control method using the switch.
2. Description of the Related Art
A computer system performs data reading and writing whenever necessary from a host system exemplified by a CPU (Central Processing Unit) using a secondary storage device of a large capacity provided therein for storage of data required by the host system. The secondary storage device is often a nonvolatile storage medium, popularly, a disk device exemplified by a magnetic disk drive, an optical disk drive, and others.
In recent years, such a secondary storage device has been expected to be better in performance with the current movement toward the information-oriented society. To meet such expectations, preferably, the more number of disk drives are to be connected, and the throughput is to be enhanced. As a responsive solution, so far proposed is to establish a connection between a disk controller and a disk array in a storage device using a switch. In any high-performance storage devices, a Fibre Channel is a popular option as an input/output interface between the disk controller and the disk array.
As an example, U.S. Pat. No. 6,160,813 A1 discloses a Fibre Channel switch applicable for connection establishment between a disk controller and a disk array in a storage device. The disclosed switch is of a shared memory type, with which incoming and outgoing frames from/to every switch port share the same central memory.
As another example, U.S. 2003/191891 A1 discloses a storage device using a switch with buffer memory for connection between a disk controller and a disk array therein. More specifically, a plurality of switches SW1 to SW4 are used to connect between a disk adapter DKA and a disk array DA, which is structured by a plurality of disk groups R1 to R4. The switches are in charge of switching between a port connected with the disk adapter and a port connected with a disk drive for every incoming frame. Such switching is performed in accordance with destination information in each corresponding frame.